Spiral fuel flow restrictor



1967 .1. M. BLAKELY ETAL 3,337,135

SPIRAL FUEL FLOW RESTRICTOR Filed March 15, 1965 INVENTORS w/m /IZBL 44 50 BY P055271} 021/0104;-

United States. Patent 3,337,135 SPIRAL FUEL FLOW RESTRICTOR James M. Blakely, Costa Mesa, Calif., and Robert E. Schurig, Hasbrouck Heights, N..I., assignors to Sonic Development Corporation of America, Yonkers, N.Y.

Filed Mar. 15, 1965, Ser. No. 439,738 Claims. (Cl. 239--102) This invention relates to fluid feed arrangements for atomizers; more particularly, the present invention relates to fuel feeding arrangements for use in fuel-burning atomizers utilizing sonic energy in theatomization process.

The invention may be understood most easily by first referring to the drawings, in. which:

FIGURE 1 is a perspective, partially-broken away view of a fuel-burning atomizer in accordance with the invention;

FIGURE 2 is a cross-sectional view taken along line 22 of FIGURE 1;

FIGURE 3 is a cross-sectional view taken along line 33 of FIGURE 2;

FIGURE -4 is a cross-sectional view taken along line 4-4 of FIGURE 2, and includes a schematic diagram of the system used for pumping fuel to the atomizer; and

FIGURE 5 is a cross-sectional view taken along line 55 of FIGURE 2.

The atomizer shown in the drawings is constructed in accordance with the teacchings of co-pending US. patent applications Ser. No. 260,738 filed Feb. 25, 1963, now Patent No. 3,240,253, and Ser. No. 332,502 filed December 23, 1963, now Patent No. 3,240,254, whose disclosures hereby are incorporated in the present application. Thus, atomizer 10 includes a nozzle member 12 having a compressed gas-receiving section 14, a converging inlet section 16, a cylindrical stabilizing section 18, and a diverging exit or outlet section 20. Nozzle member 12 is adapted to convert pressurized gas, e.g. air, into a high-speed gas stream which is issued into the ambient air with an internal pressure at the exit of the nozzle less than the pressure of the ambient medium. The high-speed stream or jet is directed into a pulsator or resonator cavity 22 in a support member 24.

Liquid to be atomized is delivered into the gas stream through a pair of opposed feed holds 26 and 28 which are aligned in a direction perpendicular to the longitudinal axis of the nozzle and which exit into the stabilizing section 18.

In accordance with the above-identified patent applications, this arrangement develops sonic pressure waves Whose magnitude is increased by means of resonant amplification in cavity 22. The liquid input to the atomizer is believed to be atomized by the combined forces of the shock waves in the high-speed gas stream and the amplified sonic pressure Waves. The liquid is broken up into very small droplets of highly uniform size. The low pressure at the nozzle exit causes implosion of ambient gas (air) into the jet and greatly improves the atomization.

When a combustible liquid fuel is atomized in the atomizer, and the resulting spray is ignited, a flame with unrivaled qualities is produced. Combustion in the flame is virtually complete, and it is very diflicult to extinguish. What is more,.because of the opposed dual liquid feed passages, the flame has a fan or flattened shape Well suiting the burner for use in such equipment as gas turbines.

One extremely beneficial feature of the atomizer 10 is that the fuel feed passages 26 and 28 are comparatively quite large in diameter. Thus, they do not easily become clogged by foreign particles in the fuel and only a relatively low liquid supply pressure is needed to feed liquids through the holes 26 and 28 at a satisfactorily high rate.

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Another extremely beneficial feature of this atomizer is that it can be and often is used with very low pressures for the gas which is input to the nozzle 12. For example, in many uses, such as in gas turbines, the input gas pressure ranges from less than one-half p.s.i.g. (pounds per square inch gage) to no more than five p.s.i.g. Under such circumstances the pressure at the exit of the feed-holes 26 and 28 often is below atmospheric pressure, with the result that fuel is drawn into the nozzle by the low pressure and positive pressure is not needed.

Although the low fuel-feed pressure requirement of the atomizer 10 is a distinct advantage, when the atomizer is used in combination with many fuel-feed control systems, special problems arise. Such control systems often use the pressure at the input of the atomizer, i.e., the back pressure from the atomizer, as an input signal to the control system. Since the fluid pumps controlled by such systems often supply relatively high output pressures, they quite often require a similarly high-pressure input signal from the atomizer. If the back-pressure signal is not sufiiciently high, the control system often tends to hunt or be unstable, with the results that the fuel is fed quite unevenly and the flame fluctuates in a similar manner.

Thus, in the past it has been the practice to insert an orifice or line restrictor in the fuel feed line so as to provide a high back pressure signal to the control system. However, this has a very serious disadvantage in that the restrictor must have an orifice of a diameter smaller than that of the tube in which it is located, thus making it a prime source of clogging. In fact, if such a restrictor were to be used in connection with an atomizer having large liquid feed passages such as in applicants atomizer 10, the anticlogging benefits of the large passages would be lost.

Accordingly, one object of the present invention is to provide an improved atomizer feed system which does not easily become clogged.

Another object of the present invention is to provide a clog-resistant feed system which provides a relatively high back pressure at the atomizer feed input so as to provide a relatively high input signal to a feed control system.

A further object of the present invention is to provide such a feed system adapted to feed fluids to atomizers requiring relatively low or no fluid feed pressure.

An even further object of the present invention is to provide such a feed system which is compact, simple, and

trouble-free.

Referring especially to FIGURE 2, the liquid feed structure which meets these objects includes an inner sleeve 30 which is fitted onto a cylindrical portion of the outside of nozzle member 12 and abuts a shoulder near the forward or downstream end of nozzle member 12. An outer sleeve 32 is fitted onto the exterior surface of inner sleeve 30 and is secured at its downstream end to a raised annular portion 34 of the nozzle member 12. Between the downstream end of inner sleeve 30 and the shoulder formed by annular portion 34 of nozzle member12 is a raised land forming an annular groove or passageway 36. The inlet openings of fluid feed pass-ages 26 and 28 are located within the groove 36.

An annular groove 38 in the upstream end of inner sleeve '30 forms an annular fluid inlet passageway. Passageway 38 communicates with a pipe coupling 40 which forms a part of outer sleeve 32.

As is shown in FIGURE 4, fuel is pumped into the inlet coupling 40 by means of a high pressure pump and contr-ol system 43. The back-pressure of the fuel in inlet passageway 38 is sensed by the control system and is used as an input signal.

In accordance with the present invention, the back pres sure in passageway 38 is made quite high by providing a Patented Aug. 22, 1967 pair of parallel helical grooves 42 and 44 in the outer surface of sleeve 30. Grooves 42 and 44 form, with sleeve 32,- elongated, winding flow-resisting fluid flow tubes connected between inlet passageway 38 and feed holes 26 and 28.

As is seen in FIGURE 3, the exit openings 46 and 48 of the helical passages 42 and 44 are spaced 180 apart from one another and along an axis 90 from the axis of holes 26 and 28 so as to provide symmetrical fuel feed to the holes 26 and 28. Similarly, as is shown in FIGURE 4, the inlet openings 50 and 52 to helical passages 42 and 44 are located 180 apart and 90 from the inlet coupling 40 so as to maintain even feeding at the inlet.

Groove-s 42 and 44 preferably are cut into sleeve 30 as threads and are square in cross section. Each groove has a uniform cross-sectional area along its length. Preferably, the grooves 42 and 44 are equal to one another in cross-sectional area, but their areas deliberately may be made unequal in order to alter the shape of the spray or flame emitted by the atomizer. The bottoms of grooves 42 and 44 are even with the land forming the bottom of outlet groove 36, and with the bottom of groove 38 so as to provide a smooth, continuous bottom wall for the inlet and outlet to grooves 42 and 44.

Each helical groove 42 or 44 provides frictional resistance to the flow of fluid through it. The length of each groove is set at a value sufficient to provide the desired back pressure in the inlet passageway 38. For example, in a typical installation of the atomizer in a gas turbine, the grooves 42 and 44 provide a pressure of 60 or more p.s.i.g. at their input but very low pressures at their output Grooves 42 and 44 advantageously provide a relative amount of pressure drop in a relatively small space. The inner sleeve into which the threads 42 and 44 are out forms a part of the cylindrical nozzle structure so that the grooves 42 and 44 can be made quite long and yet require very little space that would not ordinarily be required for the atomizer itself.

Most importantly, the cross-sectional area of grooves 42 and 44 is large relative to the orifice diameter of a conventional line restrictor which might be suggested for use in providing the desired pressure drop. Thus, grooves 42 and 44 easily pass fuels containing large quantities of contaminants without clogging whereas other more conventional atomizers quickly become inoperative due to clogging when using the same fuels.

As a result of the foregoing, the atomizer 10 has been successfully used as a gas turbine burner nozzle. It has been tested against conventional nozzles using small orifices through which the fuel is forced under high pressure. For example, in actual tests of a gas turbine using ten of applicants fuel-burning atomizers 10, the turbine has operated for over ten continuous hours using fuels with large amounts of solid particles (sand, etc.) without showing any signs of clogging. In comparison, when the same turbine was operated with the same fuels and ten of the burner nozzles previously used in the turbine, it operated for only a matter of a few minutes before the turbine became inoperative due to clogging of the fuel feed passages of the nozzles.

What is more, in the above-described tests the flame produced by applicants nozzles was quite substantially hotter than the flame provided by the prior nozzles. What is more, fuels of widely different viscosities were used with equal success in applicants nozzles whereas the prior nozzles would effectively burn only relatively volatile fuels such as kerosene. Moreover, the fuels successfully used in applicants nozzles were relatively cheap fuels such as Nos. 2, 4 and 6 fuel oils. In fact, then, the use of applicants nozzles makes it possible to use low cost fuels in the turbine and save considerably in fuel costs.

Another advantage of applicants atomizer 10 is that it is capable of operating at very low air input pressures, e.g. pressures well below /2 p.s.i.g. Thus, the pressure of the air supplied by the ordinary turbine compressor is more than suflicient to supply the atomizer gas without further compression.

Still another advantage of applicants fuel-burning atomizer 10 is that it gives a. flat-shaped flame pattern having its widest cross-sectional dimension in the direction of the axis of holes 26 and 28. This flat flame gives an improved turbine burner flame in that a number of the atomizers can be arranged in a circular pattern with their wide flames aligned side-to-side in a gas turbine burner compartment to produce a substantially continuous ring of flame with relatively minor temperature variations around the ring. This even flame temperature distribution provides greatly improved performance for the turbine. The wide-spread flame issuing from each atomizer causes considerable overlapping between adjacent flames and creates this even distribution.

The above description of the invention is intended to be illustrative and not limiting. Various changes or modifications in the embodments descrbed may occur to those skilled in the art and these can be made without departing from the spirit or scope of the invention as set forth in the claims.

We claim:

1. An atomizer having a nozzle with a diverging exit section for accelerating and expanding a compressed gas to speeds greater than Mach 1.0 and pressures lower than that of the ambient gaseous medium, means for delivering liquids to be atomized into the gas stream created by said nozzle, pulsator means positioned so as to intercept the expanded and accelerated gas stream emerging from said nozzle and generate sonic pressure Waves in said ambient medium, said liquid delivering means including a pair of substantially parallel elongated helical restricted liquid flow passageways of substantially constant crosssectional area, said flow passageways being adapted to pro vide frictional resistance to the flow of said liquids through them, each of said passageways starting and ending at 10- cations approximately distant from one another, and a pair of chambers, one of said chambers communicating with the exits of said passageways and the other of said chambers communicating with the inlets of said passageways.

2. Apparatus as in claim 1 in which said helical passageways are cut into the surface of a sleeve member which is fitted onto the body of said nozzle, and in which at least two opposed feed holes are located in said annular passageway and exit into said nozzle in one of its sections having a substantially constant cross-sectional area along its length.

3. Fuel burning apparatus. comprising, in combination, an atomizer having a nozzle with a diverging exitsection for accelerating and expanding a compressed gas to speeds greater than Mach 1.0 and pressures lower than that of the ambient gaseous medium, said diverging nozzle section being frusto-conical in shape, said nozzle also having a converging frustro-conical inlet section and a generally cylindrical stabilizing section joining said inlet and diverging sections, said nozzle having an external cylindrical portion with a first shoulder, a pair of diametrically opposed liquid feed holes passing through the wall of said nozzle adjacent said first shoulder and exiting into said stabilizing section, a first sleeve member fitted onto said cylindrical external surface of said nozzle and abutting said first shoulder, said first sleeve member having a pair of parallel helical grooves cut into its external surface, the crosssectional shape of said grooves being generally rectangular and the cross-sectional area of each of said grooves being essentially constant along its length, with the inlet ends of said grooves being positioned diametrically opposite one another and the outlet ends of said grooves also being being positioned diametrically opposite one another, an annular recess in the exterior surface of said first sleeve member upstream from and communicating with said inlet ends of said grooves, a second sleeve member fitted upon said first sleeve member and upon a second shoulder of said nozzle, said second shoulder extending outwardly beyond and being located downstream from said first shoulder, said second sleeve member having an inlet opening communicating with said annular groove in said first sleeve, said second sleeve forming with said annular groove an annular liquid storage chamber having said inlet ends of said helical grooves at its exit ports, the height of said first shoulder being approximately equal to the distance from the bottom of said helical grooves to the internal surface of said first sleeve member so as to form with said second sleeve member a second liquid storage chamber communicating with said feed holes.

4. In an atomizer, conduit means for conducting liquids to said atomizer, said conduit means being adapted to conduct said liquids to said atomizer under relatively low feed pressures, and pump means for supplying liquids under relatively high pressure, flow retarding means connected between said conduit means and said pump means, said flow retarding means including a member having an elongated restricted flow passage of substantially constant cross-sectional area along its "length for producing a relatively high back-pressure at its inlet, the smallest crossseCtiOnal dimension of said restricted flow passage being no smaller than the smallest cross-sectional dimension of a flow passage of said conduit means, said pump means including control means for sensing said back-pressure and controlling the liquid flow provided by said pump means in response to said back-pressure.

5. Apparatus as in claim 4 in which said atomizer has a nozzle with a diverging exit section for accelerating and expanding a compressed gas to speeds greater than Mach 1.0 and pressures lower than that of the ambient gaseous medium, means for delivering liquids to be atomized into the gas stream created by said nozzle, pulsator means for accelerating and expanding a compressed gas to speeds greater than Mach 1.0 and pressures lower than that of the ambient gaseous medium, means for delivering liquids to be atomized into the gas stream created by said nozzle, pulsator means positioned so as to intercept the expanded and accelerated gas stream emerging from said nozzle and generate sonic pressure Waves in said ambient medium, said liquid delivering means being connected to said conduit means to receive a liquid therefrom.

References Cited UNITED STATES PATENTS 20 1,413,134 4/1922 Purnell 239-402 3,240,253 3/1966 Hughes 158--4 3,240,254 3/ 1966 Hughes 1,584

FOREIGN PATENTS 458,606 8/1913 France. 257,687 9/ 1926 Great Britain.

EVERETT W. KIRBY, Primary Examiner. 

1. AN ATOMIZER HAVING A NOZZLE WITH A DIVERGING EXIT SECTION FOR ACCELERATING AND EXPANDING A COMPRESSED GAS TO SPEEDS GREATER THAN MACH 1.0 AND PRESSURE LOWER THAN THAT OF THE AMBIENT GASEOUS MEDIUM, MEANS FOR DELIVERING LIQUIDS TO BE ATOMIZED INTO THE GAS STREAM CREATED BY SAID NOZZLE, PULSATOR MEANS POSITIONED SO AS TO INTERCEPT THE EXPANDED AND ACCELERATED GAS STREAM EMERGING FROM SAID NOZZLE AND GENERATE SONIC PRESSURE WAVES IN SAID AMBIENT MEDIUM, SAID LIQUID DELIVERING MEANS INCLUDING A PAIR OF SUBSTANTIALLY PARALLEL ELONGATED HELICAL RESTRICTED LIQUID FLOW PASSAGEWAYS OF SUBSTANTIALLY CONSTANT CROSSSECTIONAL AREA, SAID FLOW PASSAGEWAYS BEING ADAPTED TO PROVIDE FRICTIONAL RESISTANCE TO THE FLOW OF SAID LIQUIDS THROUGH THEM, EACH OF SAID PASSAGEWAYS STARTING AND ENDING AT LOCATIONS APPROXIMATELY 180* DISTANT FROM ONE ANOTHER, AND A PAIR OF CHAMBERS, ONE OF SAID CHAMBERS COMMUNICATING WITH THE EXITS OF SAID PASSAGEWAYS AND THE OTHER OF SAID CHAMBERS COMMUNICATING WITH THE INLETS OF SAID PASSAGEWAYS. 